Theoretical Framework

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THEORICAL FRAMEWORK

THEORIES ON THE NATURAL HISTORY OF BREAST CANCER

1. The Halsted Theory: Spread from One Source

For 60 years, starting in 1894 (or perhaps earlier), breast cancer was seen in medical literature to be a disease that arose in one location (the breast) and, if left untreated, spread through the lymphatic system first to nearby lymph nodes and subsequently to other organs in the body. This theory of "contiguous" development of metastases was articulated by Dr. W.S. Halsted, inventor of the Halsted radical mastectomy. It has thus become known as the Halsted theory, Halsted hypothesis, Halsted paradigm, Halsted model, or "halstedian view."

2. The Alternative Theory: Systemic Disease

In 1954 and 1967 an alternative theory was formulated and, after studies were done, was put forth in rather definitive terms in a 1980 lecture by Dr. Bernard Fisher. He stated "that breast cancer is a systemic disease . . . and that variations in effective local regional treatment are unlikely to affect survival substantially." Following the therapeutic implications of this "systemic theory," the systemic disease has been attacked in recent years by chemotherapy and hormone therapy to the whole body. Under a pure version of this theory, the only purpose of so-called "local or regional control" (breast surgery and local or regional radiotherapy) is to prevent a local tumor from getting out of hand and causing harm in that location, not to prevent future metastases to other parts of the body. That is, under this theory any distant metastases of any significant have already occurred at the time that a breast tumor is found by touch (palpation) or in a mammogram

3. Citizens and Doctors, Halsted or Systemic Theories

I think that the average citizen instinctively holds a basically Halstedian theory in her mind. One commonly hears the notion that "getting the tumor out" is the most important step. Chemotherapy is seen as a kind of "mopping up operation" in case any metastases had occurred earlier from the breast to other parts of the body (the contiguous route for development of tumors). I know that I was quite surprised when I learned that my friend's oncologist recommended delaying surgery while doing chemotherapy, something that seemed contrary to the goal of getting rid of the "main problem" first. Subsequently, I came to understand that to do surgery first can actually be viewed as delaying chemotherapy, and why one might want to do the chemotherapy first. trained in the past 15-20 years are more likely to have been trained under the "systemic theory," in which distant metastases of some size are considered to be probable in the case of any breast cancer that has been detected (other than DCIS, ductal carcinoma in situ). Such doctors may instinctively discount the new studies showing a *survival* advantage in some women from having radiotherapy after a mastectomy (though they seem to have little problem with studies showing survival advantages from radiotherapy that follows lumpectomies). Or perhaps some of those who accept the evidence that radiation after lumpectomy improves survival statistics, but do not conceive of getting survival advantages from radiation after mastectomy, hold a basically Halstedian viewpoint, but cannot imagine what tumor burden might be left after a mastectomy with clean margins. At any rate, what are we to make of the facts that (a) controlling regional disease with radiation after mastectomy helps some women survive longer (meaning that the site from which "secondary dissemination" could have occurred got eradicated by the radiotherapy -- a neo-Halstedian fact, perhaps you could call it) and (b) controlling distant disease with chemotherapy and/or tamoxifen helps some women survive longer (meaning that the disease had already disseminated or was systemic in the first place -- a systemic-theory-supporting fact)? One answer could be to construct a theory or hypothesis that accounts for both kinds of therapy successes. Dr. Samuel Hellman of the University of Chicago did just this in a 1994 lecture, and labeled it a "spectrum theory."

4. The Spectrum Theory, or Combined Theory

In the 1994 Karnofsky Memorial Lecture, Dr. Hellman reviewed the history of theories of breast cancer development ("natural history") from 1894 to present, and then proceeded to state the case for what he calls the "spectrum theory." My discussion of the Halsted and systemic theories, above, is based in part on his lecture. One of the reasons that he felt called upon to formulate a new theory was that the studies showing a survival benefit from radiation therapy after mastectomies could not be adequately explained by the reigning systemic theory that has the attention of most oncologists -- yet he believes that the studies, regardless of any limitations they may have, are providing important information that should not be ignored. Since data that contradicts a reigning theory can sometimes be disregarded, he thought it important to describe why it is the current theory (the "conventional wisdom") that should yield, not the data.